Identifying Molecular Orientation of IndividualC60on aSi(111)−(7×7)Surface

Low temperature scanning tunneling microscopy (STM) has been used to identify the molecular orientation of individual ${\mathrm{C}}_{60}$ on $\mathrm{Si}\left(111\right)-(7\times 7)$ surfaces. The STM images of individual ${\mathrm{C}}_{60}$ reveal clear and rich intramolecular features that are site and bias dependent. Theoretical simulations, using the local density approximation method with cluster models, uniquely reproduce the observed STM images and hence allow the unambiguous identification of the binding configurations of the adsorbed fullerenes with respect to the Si substrate.